U.S. patent number 7,006,499 [Application Number 10/742,226] was granted by the patent office on 2006-02-28 for source identifier for mac address learning.
This patent grant is currently assigned to Alcatel IP Networks, Inc.. Invention is credited to Joe Regan, Nicholas W. Tingle.
United States Patent |
7,006,499 |
Tingle , et al. |
February 28, 2006 |
Source identifier for MAC address learning
Abstract
A header value or label, referred to herein as a source station
identification (SSID), is added to an encapsulated packet header,
such as by adding the SSID as a label to the bottom of a stack of
MPLS labels. The SSID comprises a unique identifier that identifies
the PE that originated the packet. In some embodiments, the IP
address of the originating PE may be used as the SSID for that PE.
The PE receiving this packet can then associate the source Ethernet
MAC address of received TLS traffic, e.g., with the originating PE.
Given the SSID of the originating PE, the receiving PE is able to
determine which LSP to use to send Ethernet traffic to the station
with the learned MAC address.
Inventors: |
Tingle; Nicholas W. (San Jose,
CA), Regan; Joe (Pleasanton, CA) |
Assignee: |
Alcatel IP Networks, Inc.
(Plano, TX)
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Family
ID: |
33303328 |
Appl.
No.: |
10/742,226 |
Filed: |
December 18, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20040213228 A1 |
Oct 28, 2004 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60466245 |
Apr 28, 2003 |
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Current U.S.
Class: |
370/392; 370/465;
370/396; 370/352 |
Current CPC
Class: |
H04L
12/4633 (20130101); H04L 45/00 (20130101); H04L
12/462 (20130101); H04L 45/50 (20130101); H04L
45/04 (20130101) |
Current International
Class: |
H04L
12/28 (20060101); H04J 3/16 (20060101); H04L
12/66 (20060101) |
Field of
Search: |
;370/395.3,395.31,389,390,392,400,352,396,465,467,469,395.5
;709/238,239,242,246 |
References Cited
[Referenced By]
U.S. Patent Documents
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5959990 |
September 1999 |
Frantz et al. |
5996021 |
November 1999 |
Civanlar et al. |
6449279 |
September 2002 |
Belser et al. |
6603768 |
August 2003 |
Bleszynski et al. |
6693878 |
February 2004 |
Daruwalla et al. |
6728232 |
April 2004 |
Hasty, Jr. et al. |
6788681 |
September 2004 |
Hurren et al. |
6859842 |
February 2005 |
Nakamichi et al. |
6862286 |
March 2005 |
Tams et al. |
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Primary Examiner: Nguyen; Hanh
Attorney, Agent or Firm: Van Pelt, Yi & James LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Patent
Application No. 60/466,245 entitled "Source identifier for MAC
address learning over a point-to-multipoint label switched path"
filed Apr. 28, 2003, which is incorporated herein by reference for
all purposes.
Claims
What is claimed is:
1. A method for routing data between an originating station and a
destination station using a protocol under which the identity of
the originating station may not be apparent to the destination
station, the data comprising a source address associated with a
node that originally sent the data, comprising: adding a source
station identifier associated with the originating station to a
header associated with the data; and forwarding the packet from the
originating station to the destination station; wherein: the
originating station is different from the node that originally sent
the data; the format and required content of the header is
prescribed by the protocol; and adding the source station
identifier associated with the originating station to the header
comprises adding the source station identifier in a manner that
does not interfere with the format and required content of the
header required for the normal processing of the header under the
protocol.
2. A method for routing data as recited in claim 1 wherein the
protocol comprises the multiple protocol label switching (MPLS)
protocol and adding a source station identifier associated with the
originating station to the header comprises inserting the source
station identifier as an additional label at the bottom of the MPLS
label stack.
3. A method for routing data as recited in claim 1 wherein the
source station identifier comprises the IP address of the
originating station.
4. A system for routing data between an originating station and a
destination station using a protocol under which the identity of
the originating station may not be apparent to the destination
station, the data comprising a source address associated with a
node that originally sent the data, comprising: a communication
interface; and a processor configured to add a source station
identifier associated with the originating station to a header
associated with the data and forward the packet from the
originating station to the destination station via the
communication interface; wherein: the originating station is
different from the node that originally sent the data; the format
and required content of the header is prescribed by the protocol;
and adding the source station identifier associated with the
originating station to the header comprises adding the source
station identifier in a manner that does not interfere with the
format and required content of the header required for the normal
processing of the header under the protocol.
5. A system for routing data as recited in claim 4 wherein the
protocol comprises the multiple protocol label switching (MPLS)
protocol and adding a source station identifier associated with the
originating station to the header comprises inserting the source
station identifier as an additional label at the bottom of the MPLS
label stack.
6. A system for routing data as recited in claim 4 wherein the
source station identifier comprises the IP address of the
originating station.
7. A computer program product for routing data between an
originating station and a destination station using a protocol
under which the identity of the originating station may not be
apparent to the destination station, the data comprising a source
address associated with a node that originally sent the data, the
computer program product being embodied in a computer readable
medium and comprising computer instructions for: adding a source
station identifier associated with the originating station to a
header associated with the data; and forwarding the packet from the
originating station to the destination station; wherein: the
originating station is different from the node that originally sent
the data; the format and required content of the header is
prescribed by the protocol; and adding the source station
identifier associated with the originating station to the header
comprises adding the source station identifier in a manner that
does not interfere with the format and required content of the
header required for the normal processing of the header under the
protocol.
8. A computer program product for routing data as recited in claim
7 wherein the protocol comprises the multiple protocol label
switching (MPLS) protocol and adding a source station identifier
associated with the originating station to the header comprises
inserting the source station identifier as an additional label at
the bottom of the MPLS label stack.
9. A computer program product for routing data as recited in claim
7 wherein the source station identifier comprises the IP address of
the originating station.
Description
FIELD OF THE INVENTION
The present invention relates generally to data routing and
networks. More specifically, a source identifier for MAC address
learning over a multipoint-to-point label switched path is
disclosed.
BACKGROUND OF THE INVENTION
Organizations and enterprises generate significant revenue by
delivering data communication services based on quality of service
(QoS), which has become an important metric upon which billing is
based. In order to improve or maintain QoS, services such as leased
lines, virtual leased lines (VLLs), virtual private networks
(VPNs), virtual private LAN services (VPLS), and others provide
dedicated data communication systems. These systems provide a
"dedicated" path tunnel, which can be a virtual circuit (VC) for
data communication between two or more customer networks that are
not locally connected.
One typical approach is to define label switched paths (LSPs)
through which traffic to a particular destination or set of
destinations serviced by a particular provider edge (PE) router may
be tunneled. Where multiple locations may need to be able to send
traffic to the destination, a multipoint-to-point (sometimes
referred to herein by the abbreviation "MP2P") LSP may be defined.
In MPLS (multi-protocol label switching), an LSP is typically MP2P.
LSPs can also be used for point-to-point (P2P) applications and
typically result from the use of label switching and the
unidirectional nature of LSPs. In such a MP2P LSP, a plurality of
defined paths from the originating PE's associated with ingress
tunnel endpoints converge onto a single path entering the
destination PE. A problem arises, however, in that the destination
PE must have a way of learning the identity of the originating PE
and associating that PE with the source MAC address of a received
packet, e.g., in order to know how to route traffic sent to that
source MAC address. When MPLS or MPLS versions of existing
protocols (e.g., RSVP-TE, LDP, MP-BGP, etc.) are used to implement
an LSP, the destination (receiving) PE does not have any way of
knowing which PE originated the packet, as each node along the LSP
uses its own label to forward packets to the next node, with the
result that the receiving PE can identify through the primary label
only the core device that forwarded the packet to the receiving PE
along the last hop or leg of the LSP.
Conventional multipoint-to-point implementations require overlays
of virtual tunnels to resolve this problem. In particular, in one
typical approach a separate VC label is assigned per source PE for
each service. In general, the typical approach solves a source
identification problem and the multiplexing of traffic for
different VPNs using the same transport. However, it does not
reduce the number of labels. This approach is disadvantageous
because of the overhead and complexity associated with assigning,
managing, and routing packets using such a large number of labels.
To quantify the shortcoming, if a separate VC label is assigned for
each of "n" PE devices or nodes associated with a particular
customer or service, for example, the number of labels per service
would be on the order of n.sup.2 (specifically n(n-1)), as each
node would be required to have a separate virtual point-to-point
circuit to each other node. By contrast, if the destination PE had
a way of identifying the originating PE without requiring that a
separate VC label be assigned for each PE for each service, each of
the n PE devices would require only one label per service, so that
only n labels would be required.
Thus, it would be useful for a solution to solve how to determine a
source station's address without creating an additional layer or
mesh of tunnels for a MP2P LSP.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of the invention are disclosed in the following
detailed description and the accompanying drawings.
FIG. 1A illustrates a system for learning a MAC address;
FIG. 1B illustrates a system for learning a MAC address, showing a
FIB;
FIG. 2 illustrates an exemplary packet header including a source
identifier for learning a MAC address; and
FIG. 3 illustrates a process for associating an identifier with a
source MAC address.
DETAILED DESCRIPTION
The invention can be implemented in numerous ways, including as a
process, an apparatus, a system, a composition of matter, a
computer readable medium such as a computer readable storage medium
or a computer network wherein program instructions are sent over
optical or electronic communication links. In this specification,
these implementations, or any other form that the invention may
take, may be referred to as techniques. In general, the order of
the steps of disclosed processes may be altered within the scope of
the invention.
A detailed description of one or more embodiments of the invention
is provided below along with accompanying figures that illustrate
the principles of the invention. The invention is described in
connection with such embodiments, but the invention is not limited
to any embodiment. The scope of the invention is limited only by
the claims and the invention encompasses numerous alternatives,
modifications and equivalents. Numerous specific details are set
forth in the following description in order to provide a thorough
understanding of the invention. These details are provided for the
purpose of example and invention may be practiced according to the
claims without some or all of these specific details. For the
purpose of clarity, technical material that is known in the
technical fields related to the invention has not been described in
detail so that the invention is not unnecessarily obscured.
Multipoint-to-point routing of data without an overlay or mesh of
dedicated path tunnels provides desirable scaling, signaling, and
provisioning properties. A header value or label referred to herein
as a source station identification (SSID) is added to an
encapsulated packet header, such as by adding the SSID as a label
to the bottom of a stack of MPLS labels, or as a control worded
added between the MPLS header and the VPN data. The SSID comprises
a unique identifier that identifies the PE that originated the
packet. In some embodiments, the IP address of the originating PE
may be used as the SSID for that PE. The IP address may be included
as a control word between the MPLS header and the VPN data. The PE
receiving this packet can then associate the source Ethernet MAC
address of received TLS traffic, e.g., with the originating PE.
Given the IP address of the originating PE it is able to determine
which LSP to use to send Ethernet traffic to the station with the
learned MAC address. Using the techniques below,
multipoint-to-point LSPs can be used more effectively for TLS,
VPLS, HVPLS (hierarchical virtual private LAN services), and other
services. This enables scaling of LSPs to occur as an order of "n"
instead of "n.sup.2", as in conventional implementation as
described above. Signaling protocols such as RSVP and BGP can be
used to distribute labels in a simple manner and simplified
provisioning occurs because a single destination label is assigned
per PE for each service.
FIG. 1A illustrates a system for learning a MAC address. System 100
represents a series of data paths that extend across service
provider network 101. Within service provider network 101 are core
routers 102 108. Although shown with 4 core routers, in other
backbones, fewer or more core routers may be used. At the edges of
service provider network 101 are a series of PEs 110 120. PEs 110
120 provide ingress/egress points into/out of service provider
network 101 for customer edge (CE) devices 122 138. CEs 122, 124,
128, and 138 are associated with a particular customer and/or
service and provide further routing to destinations associated with
the customer and/or service. As used herein, the term "router"
refers to any equipment used to route data from a source to a
destination, and may include any node within a customer or provider
network that performs such a routing function. Here, destinations
A1, A2, B, C, and D are examples of destinations that route data
traffic through CEs 122, 124, 128, and 138. The system is
configured, in this example, similar to an "inverted tree" or
multipoint-to-point configuration where source stations A1, A2, C,
and D are in data communication with destination station B, with
traffic from stations A1, A2, C, and D destined for station B being
transported over a multipoint-to-point LSP 139, shown in FIG. 1A as
a series of arrows in dashed lines originating at PE 110 and PE 114
and terminating at PE 120, through which PEs 110 and 114 are
configured to send traffic to PE 120. Similarly, traffic for
stations associated with PE 110, e.g., A1, A2, and C, would be sent
from stations B or D through a second multipoint-to-point LSP (not
shown in FIG. 1A) having PE 114 and PE 120 as ingress points and PE
110 as the destination PE, and traffic for stations associated with
PE 114, e.g., D, would be sent from stations A1, A2, B, or C
through a third MP2P LSP (not shown in FIG. 1A) having PE 110 and
PE 120 as ingress points and PE 114 as the destination PE. In this
manner, the locations and network stations associated with CEs 122,
124, 128, and 138 may be linked in a virtual network, such as a
virtual private LAN service, using a mesh of MP2P LSPs, whereby
customer network traffic, e.g., Ethernet traffic, is transported
between locations transparently to the users of the various
customer stations. Although only CEs 122, 124, 128, and 138 are
shown in data communication with customer networks, in other
embodiments, the number of CE routers may be different, depending
upon the backbone or network service provider (NSP), number of
customers, number of nodes, and other network-influencing
factors.
As noted above, one problem that must be addressed when using MP2P
LSPs as described herein is the need for a destination PE (i.e.,
the endpoint of a MP2P LSP) to be able to "learn" the source MAC
address of the original sender of a packet received by the PE via
the MP2P LSP and associate that MAC address with the ingress PE by
which it entered and was sent through the MP2P LSP. In an
embodiment, a source station identification (SSID) can be appended
to the header of a data packet or frame at the ingress PE, such as
by adding the SSID as an additional label at the bottom of an MPLS
label stack. Upon receipt by an egress PE, the SSID is used to
associate the MAC address for the source station that originated
the packet (e.g., the MAC address for CE 122 for a packet sent by
station A1, with the ingress PE by which it entered and was sent
through the MP2P LSP. With an SSID the number of labels distributed
per PE from one-per-VPN-per-peer-PE can be reduced to distributing
a label on the basis of one-per-VPN. If an SSID is not the IP
address of the PE router, then a separate configuration for mapping
an SSID to a PE router may be used.
The MP2P LSP shown in FIG. 1A may be used, e.g., to transport a
customer network packet sent from station A1 to station B. Such a
packet originated by station A1 would be provided to ingress PE 110
via CE 122. The packet would be encapsulated by PE 110 for
transport through the MP2P LSP to PE 120, the encapsulation
including a header comprising a VC label associated with the LSP,
and would then be routed between core routers 102, 104, and 108,
before reaching the edge of service provider network 101 at egress
PE 120. PE 120 would then de-encapsulate the packet, reconfigure it
as appropriate to the customer network, and send it to CE 138, from
which it would be delivered to destination station B. The path used
is a LSP tunnel that can be established by signaling the path to
the various routers along its length. Various types of signaling
protocols may be used and are not limited to those described herein
(e.g., BGP, RSVP, etc.). Further, other protocols other than MPLS
may be used for establishing tunnel architecture such as that
described. Greater detail is provided with regard to the routing of
data traffic is provided below in connection with FIG. 1B.
FIG. 1B illustrates a system for learning a MAC address, showing a
table 140 used to map SSIDs to an associated LSP identifier (LSP
ID) and a FIB 142 used to associated source MAC addresses with a
corresponding LSP ID for a particular VPN.
In a MP2P LSP, an LSP ID may be used to identify a dedicated
"circuit" or path from two or more ingress PEs located along the
edge of service provider network 101 to a destination PE. In the
example shown in FIGS. 1A and 1B, an LSP ID may be used to identify
the MP2P LSP connecting ingress PEs 110 and 114 with destination PE
120. Similar LSPs, identified by associated LSP IDs, may be
established to transport traffic to other PEs participating in a
particular service, such an LSP allowing PE 110 and PE 120 to send
traffic to PE 114 and an LSP used by PE 114 and PE 120 to send
traffic to PE 110. Under one typical approach, each destination PE
signals to the other PEs participating in a service, such as a
transparent LAN service, a VC label to be used to send traffic
associated with the service to that PE. For example, PE 110 may
signal to PE 114 and PE 120 that VC Label"101" should be used to
send traffic associated with the service to PE 110, and PE 114 may
signal to PE 110 and PE 120 that VC Label "302" should be used to
send traffic associated with the service to PE 114. The numbers
used in this example are completely arbitrary, and any number
suitable under the applicable protocols used to establish and
provide the LSP may be assigned.
In order to know how to route return traffic, each PE must "learn"
an association between the source MAC address in received packets
and an LSP ID associated with the ingress PE device that sent the
received packet through the MP2P LSP, i.e., each PE must populate a
FIB such as FIB 142 of FIG. 1B. In the case of PE 120, for example,
initially PE 120 populates table 140 by associating the LSP ID
signaled to it for use by each other PE participating in the
service with the SSID for that PE. In the example shown in FIG. 1B,
the table 140 has been populated with an entry associating the LSP
ID "101" with the SSID for PE 110. In table 140, the SSID is listed
as "PE110" for convenience and clarity, although as noted above the
IP address of the PE may be used as the SSID. When a packet
originated by station A1 and directed to station B is received by
PE 120, if no entry exists in FIB 142 for the associated source MAC
address an entry is created by entering the source MAC address and
associating with it the LSP ID associated with the ingress PE from
which the packet was received. PE 120 ensures that a received
packet is sent to the correct CE. However, in other embodiments, a
control word, identifier, or label could be used to identify a CE
and thus enable the PE to forward the packet without requiring an
additional MAC address lookup. As shown in FIG. 1B, this may be
accomplished by reading the SSID (included as an additional label
in the stack, e.g., as described above), using table 140 to map the
SSID to a corresponding LSP ID, and then associating that LSP ID
with the source MAC address in FIB 142. If in the future PE 120 is
required to handle outbound traffic destined for the MAC address
associated with station A1, PE 120 refers to FIB 142 to obtain the
LSP ID to be used to transport the packet to the correct PE (in
this case, PE 110).
FIG. 2 illustrates an exemplary packet header including a source
identifier for learning a MAC address. Several fields are included
in packet header 200, which represents the encapsulated data that
is used to route a packet or frame between a source and destination
station. VC label 202 indicates the virtual circuit path tunnel
that the particular data packet is intended to follow. Specific
path tunnels are provided between particular endpoints, which are
assigned based upon a specific QoS. EXP bits 204 are part of the
MPLS header, providing for an experimental value. If the
encapsulated frame is an Ethernet frame that contains an IEEE
802.1q VLAN tag, the p-bits of the tag may be mapped to the EXP
bits at the ingress tunnel endpoint. The EXP bits may be mapped
back into p-bits of a VLAN tag at the egress tunnel endpoint. S bit
206 denotes the bottom of the label stack. TTL value 208 provides a
time-to-live value of the VC label. VC label 202, EXP bits 204, and
TTL value 208 are, in this embodiment, standard components of the
MPLS header. A reserved field 210 is provided for additional header
information. Flags 212 provide a field for other labels and
identifiers that can be used to identify resources or portions of a
particular path along which data may be routed. Length 214 may be
used to define the length of certain specific fields within the
encapsulated header packet. Sequence number 216 determines the
order for the data packet or frame in order to guide reassembly
upon arrival at a destination station. Reserved field 210, flags
212, length 214, and sequence number 216 are collectively
identified as control words for use with MPLS implementations.
Finally, an additional control word is contained in SSID 218. SSID
218 is included, providing a control word that can be associated
with an originating source station (e.g., the originating PE) for
the purpose of enabling egress tunnel endpoint to "learn" MAC
address origins and associate them with transport tunnels for
outbound traffic associated with such learned MAC addresses.
Preferably, an SSID is a 4-byte field providing an identifier
associated with a source station. However, in other embodiments,
the field length may be larger or smaller. By learning the
particular source address, edge routers such as PEs 110 120 are
able to determine where a particular packet has come from and where
response packets should be directed.
FIG. 3 illustrates a process for associating a source station
identifier with a source MAC address. An identifier is added to a
packet and transmitted along a path tunnel, such as an LSP or VC
(302). The identifier may be added by an ingress endpoint of the
LSP or VC, such as by an ingress PE device. The identifier may be
any value or string that is unique to the ingress PE, such as the
IP address of the PE. Once transmitted, the packet is received at a
destination edge router (e.g., PE) (304), which associates the
identifier with a source station address (e.g., MAC address) (306).
By associating a MAC address with the identifier, an edge router
learns how to route data traffic back to an originating point
associated with the MAC address, without there having to be
established an actual or virtual point-to-point circuit or path for
each possible originating endpoint, as described above. After
associating the MAC address with the identifier, the identifier is
recorded in a FIB at the particular edge router (e.g., PE, CE)
(308). Other PEs on service provider network 101 (FIGS. 1A, 1B)
that receive the packet, e.g., in the case of a packet broadcast to
all other PEs associated with a service, may likewise "learn" the
association of the source MAC address with the identifier (e.g.,
SSID). In other embodiments, other databases, management
information bases (MIBs), or other repositories associated with the
provider edge routers (or devices) may be used to store the
identifier(s).
In conventional implementations, the inability of
MPLS-implementations to identify a source station for a received
packet an egress router is solved. Further, signaling protocols are
also affected in that fewer path tunnels need to be signaled for
setup and reservation when using an SSID. The use of an SSID also
enables services such as a transparent bridge, switch, or other TLS
to be implemented more efficiently by providing a mechanism for
learning the source station's MAC address.
Although the foregoing embodiments have been described in some
detail for purposes of clarity of understanding, the invention is
not limited to the details provided. There are many alternative
ways of implementing the invention. The disclosed embodiments are
illustrative and not restrictive.
* * * * *